In general, performing an exacting procedure on a compliant material can be difficult due to the inherent evasive nature of the material. The difficulty can be exacerbated if the compliant material is mobile. One example of an exacting procedure performed on a mobile compliant material is cardiovascular surgery performed on a beating heart. Devices and methods are available for immobilizing the heart during cardiovascular surgery. However, many available systems can have undesirable effects on the patient.
Coronary artery bypass (CABG) surgery is a technique for revascularization of the heart necessitated by coronary artery obstruction. Typically, this procedure is facilitated by reducing or stopping the motion of the heart to allow for accurate suturing of the anastamoses. Present methods for reducing or stopping the motion of the heart include pharmacological and presently available mechanical means. If the heart is stopped, cardiopulmonary bypass (CPB) equipment (heart/lung machines) is used to maintain systemic blood flow. The use of pharmacological agents, with or without CPB equipment, and presently available mechanical methods to restrain the heart have inherent disadvantages.
Pharmacological agents can be used to slow or stop the heart. Usually, these drugs are administered systemically and in the case of cardioplegic agents must have a short duration of action. One disadvantage of pharmacological slowing of the heart is that the heart continues to beat thus allowing only intermittent suturing of anastomoses between beats. In addition, cardiac slowing compromises systemic circulation to vital organs thus limiting broad application of these techniques without cardiac support.
Generally, the use of cardioplegic agents necessitates use of cardiopulmonary bypass (CPB) equipment or heart/lung machines. While complete cardiac arrest allows accurate construction of anastomoses, CPB equipment is expensive to operate and can cause significant pathophysiological effects in the patient. Examples of pathophysiological consequences which can occur with CPB equipment include cardiac consequences, neurological consequences, pulmonary dysfunction, renal dysfunction, hepatic dysfunction, coagulapathies, blood element trauma and impairment of cell-mediated immunity.
Mechanical means to stabilize the heart during cardiac surgery use compression or traction to sufficiently restrain the heart to permit anastomoses of the vessels. Known mechanical devices are disclosed in, for example, U.S. Pat. Nos. 3,983,863, 4,973,300 and 5,509,890. These devices generally stabilize a localized area of the heart by compression. However, compressive forces sufficient to stabilize the heart can functionally deform the pumping chambers of the heart and impair cardiac filling or effective pumping between cardiac contractions. Hence, cardiac output is compromised. In addition, the frictional forces exerted by some devices during restraint can cause tearing or abrasion of the epicardial surface of the heart. Moreover, these devices have a limited range of access thus limiting utility of such devices to situations where only one or at most two adjacent arteries are to be bypassed.
Accordingly, there is a need for devices and methods to stabilize a compliant body during performance of an exacting procedure. In the case of living organs, there is a need to stabilize the organ without significantly compromising normal physiological function and without inducing trauma to the organ or the patient. Moreover, there is a need for devices and methods to perform exacting procedures on living organs without the use of costly patient support systems.